Storing up a future problem

Features editor

The lack of clarity over whose responsibility it is to build and operate grid-connected energy storage could hold up the establishment of this new, important part of the electricity network. Several technologies are available for deployment, but there needs to be much more discussion of how they will fit into the system, technically and financially.

We’ve written a lot about the various different types of electricity generation technologies in The Engineer, and it never fails to stir up debate. Proponents and opponents of wind, wave, tidal, nuclear and fossil-fuel generation argue back and forth, but the simple fact is that we need a mix of all types of generation technologies to balance security of supply, sustainable use of fuels and affordability.

Despite the unpredictable pronouncements of certain energy ministers, government policy has pretty much followed this idea for some years. But the energy landscape is complicated, and it’s becoming apparent that there needs to be a great deal more coordination between the energy stakeholders if we’re to have a fit-for-purpose network in the coming decades.

The part of the energy landscape that hasn’t received much attention is energy storage. It’s rarely mentioned, apart from as a stick with which to beat renewables — they won’t be reliable unless there is energy storage to counter their intermittency and, the argument goes, the technologies to store power just aren’t there.

In fact, this isn’t true. Flywheel technology is sufficiently advanced for a 20MW plant to be installed in New York State. Pumped storage has been used in the UK for many years, as anyone who’s visited the enormous ‘Electric Mountain’ facility at Dinorwig in Snowdonia will know. And technologies such as energy storage by air liquefaction are well under development.

There are two main problems, it seems. First, while the technologies exist, they tend to be expensive — extra facilities on the energy network are going to cost someone money, and it’ll inevitably end up being the people who pay the bills: that is, industry and the public. Related to that, in the UK’s fragmented, fractious, deregulated energy market, nobody seems to know exactly whose job it is to set up, operate and maintain energy storage facilities. Energy generators think it’s a network issue, therefore must be the distributors’ job. Distributors think it’s part of the energy supply landscape, and therefore it’s not their job. Nobody seems to be too keen to say definitively whose job it is, thereby landing them with the bill.

But it’s got to be someone’s job. Do we need a new sector within the energy market? Does this need government regulation? Is it part of a smart grid system; and if so, how should it be coordinated with the other elements of smart grids, such as intelligent appliances that can tailor their energy consumption to match demand and price?

Nobody seems to know, as I’ll explain further in an upcoming feature you’ll be able to read next week. And this is quite worrying, because the time when we’ll need such systems is approaching rapidly. Logically, they should be established at the same time as the generating facilities they’re supposed to support — and with large offshore wind farms being built now, that appears to be leaving a gap in the system. Organisations such as the IMechE and the Royal Academy of Engineering have called attention to this, and the Technology Strategy Board has an energy storage programme — but it could all be too little, too late. The focus needs to be as much on the place of energy storage in the market and the network as on perfecting and reducing the cost of the technology. Otherwise, there’s a risk of yet another energy muddle, and that’s the last thing we need.

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Right, that’s a big issue. Out here in California (USA) they are building enormous solar farms, but they still need the transmission lines to connect to the grid, so who is paying for that, as we are reeling in our budget in Washington DC? We’ve already spent, much of it blown due to bankruptcies some $90 Billion USD.

Surely this is one, at last, for the Market. What regulation would be required? The generators will want to make the best return they can on GW of capacity operating at 03:00 while the storers will want it as cheap as possible to make their technology pay. A balance will be struck.

The syn-fuel thing a week or two ago, making diesel from atmospheric CO2, is another one that will find a market through validating the anti-social hours of the windmills, night-time tides, etc., but not mentioned in your list.

It strikes me that this is a perfect opportunity to seed a new industry. Energy storage falls between the existing camps. You need to buy it when there is surplus and then sell it when there is a shortage. Set it up as a seperate entity to supply and distribution and everyone gets a chance to play.

Surely it is the generators job, they are the ones who may not have enough power at any particular time, so to have some in a storage bank is to their advantage. Since the so called green energy is the really variable one, perhaps the windmill owners should also provide the storage?

Dinorwig at 1.7GW is the largest pumped storage in the country but hardly enormous compared with a demand of up to 65GW
Foyers and Cruachan add another 700MW

The answer is to require wind or wave developers to couple their machines to an open cycle gas turbine the output of which can be varied to suit the wind or wave input so that the combined output matches demand.
No storage is then necessary

Wind powered water pumps in Holland…. Windmills I believe they are called. I think it fair to say ‘Windmill’ is now a generic term for wind powered devices using a propellor type power collector/converter.

So, let’s stick to windmills, or maybe wind powered electricity generator. They are most definitely not turbines.

And I agree the producer should provide the interim storage devices to even out their generation and delivery of electrical energy.

Or, as someone above suggested it could be contracted out to a specialised service provider. That way more than one generating company could use a single or network of storage centres.

If you are going to insist that they are not wind mills ie not windmills (one word not two) then we could all agree that they are Wind powered electricity generators and certainly not turbines as there is no outer casing.

No one has mentioned the most cost effective storage of all – molten salt. That’s a well proven, large scale storage technology already in commercial use at several solar thermal power stations. It can be applied to troughs, heliostat and dish fields to supply dispatchable power at any time of the day.

It has always struck me as odd that we don’t have significant storage in the electrical system. As far as I can see it is about the only system that does not buffer product between manufacture and use and as a result of this omission we have developed complex ways around it and built significant redundancy into the systems.

The parallel I have in my mind is water to flush your toilet. The required peak load is around 10 litres discarged in a couple of seconds through a 50mm (ish) short pipe. That is accomplished by having a store right next to the toilet in the form of the cistern. That in turn is fed by a 15mm pipe from a local supply (either a loft tank or local service resevoir.) They too are fed from other larger strategic reserves etc by comparatively small pipes. These reserves are generally fed from water captured when it rains.

The point being that the infrastructure set up allows us to harvest water in times of plenty/opportunistically and as a result we distribute it over time and through optimised infrastructure. Imagine the size of the pipes we’d have to be able to flush all the toilets simultaneously running straight off groundwater.

In terms of the impact on the grid: We know the grid is going to have to be re-designed to be based on a sustainable fuel source. Yes it will be a mix, but carbon has to come out of it over time. So the opportunity is to realise this is coming and design in storage to buffer energy during times of plenty.

It isn’t going to be easy, but there is money to be made and challenges to be solved out there! Sounds exciting to me and I look forward to the article (as always!)

Eh, by Guhm Lad, there’s trouble in’t’mill when we cannot even agree on what to call them. Actually mills are places where fibres are converted in’t fabrics. “The hand that rocks the shuttle rules t’world”
Mike B

I find that the term wind mill is often used by people who wish to denigrate wind turbines, but I think the companies who make them call them wind turbines – so I think I’ll stick with wind turbines.

On the subject of Dutch style wind powered machines. They were used for milling and sawing, and probably a few other jobs. But it could be said that they didn’t pump – as in vacuating air from a cylinder in order to pump up water. The Dutch wind machines actually flicked the water out of ditches and into rivers, they could generate very little head of water. Later, here in the UK, and method of stiring the water to raise the water level, just as it rises in a teacup until it overflows into the saucer, was invented.

The America or Chicago style wind pump, as seen in many cowboy films, and of which there is still a million in use, is always called a wind pump – by people who know what they are talking about.

National Grid are planning a series of Short Term Operating Reserve (STOR) power stations to cover dips in supply and peaks in demand. These are groups of a dozen or more 0.5MW diesel generators intended to feed to the low voltage distribution system to supply the local area. The country already has about 600MW of these but I believe the intention is to increase capacity to 1.8GW to keep the grid going if one of the next generation nuclear power stations goes off-line.

Letchworth had a planning application for one of these over the summer but it was rejected – watch out for one springing up near you.

My favourite (wackiest ?) idea is to use the volume inside wind turbine towers for pumped storage. With mercury as the working fluid you should be able to store 30 minutes of turbine output. There may be some environmental problems with this but at least a full tower wouldn’t easily blow away.

The powers that be are already planning an old technology solution to load balancing – the clever solutions may have missed the boat already.

Wind Turbines indeed! Charles Parson’s, the inventor of the steam turbine must be turning in his grave (sorry about the pun)! When did a large propeller, connected via a gear box and shaft, to an electrical generator, become a turbine?
They are simply wind powered electrical generators and it does beg the question:”Where have all the ‘true/genuine’ engineers gone?”

What happened to Thin Red Line’s CAES storage for wind turbines? I have just had a look at their site, and it seems not too much has happened, all they have is a link to your story of them. Can we cancel that bag of wind as a viable storage scheme?

This discussion of avoids the most important question of all. What renewable energy must have if it is to become large-scale is low cost efficient energy storage for days, weeks and even months.

No such technology exists, or is even on the horizon.

Spending money on storage technologies for the short term popping up of a highly subsidised and expensive method of power generation is throwing good money after bad. The fact is that, because the world has not significantly for the last 17 years, we cannot be sure that, dioxide does not cause dangerous global warming.

The real danger that the world faces is global cooling. People who study the sunspot cycles say that it is now highly likely

Turbine, noun:
a machine for producing continuous power in which a wheel or rotor, typically fitted with vanes, is made to revolve by a fast-moving flow of water, steam, gas, air, or other fluid.

Mill, noun:
1a building equipped with machinery for grinding grain into flour.
a piece of machinery for grinding grain:
a direct steam-driven flour mill
a domestic device for grinding a solid substance to powder:
a pepper mill
2a factory fitted with machinery for a particular manufacturing process:
a steel mill
a piece of manufacturing machinery.
3 informal an engine.

Derek O’s comment about the micro gen-sets is very heartening, but also depressing! Small is beautiful in my view of this context, but it should be using biomass. Rather than converting mega stations to dual fuel (today’s reports of Drax) and planning to import timber waste from N America (and prime rainforest no doubt) we should be firing big stations with concentrated fuel and small stations with diffuse fuel. Appropriate localism could include hedge trimmings, waste straw etc and a realistic amount of local forest products and by-products. Coppicing motorway margins within a few miles of each station must be able to generate massive weights of very green fuel.
It would not resolve the need for fuel deliveries (no doubt a major part of the justification for refusal at Letchworth) but at least it would have full local “ownership” along with the genuine stakeholder interest.

Wind and solar energy generators benefit from a double subsidy. Firstly electricity produced can always be sold at a fixed and very high price due to the FIT system. Secondly grid stability is provided at the expense of other non-renewable generators, who must have capital and overheads idle when the wind is blowing or the sun is shining. There is therefore no incentive for wind and solar generators to develop storage systems, so they don’t. The FIT system does exactly the opposite of what is intended – in principle it stifles innovation within the renewables sector. In practice there is little prospect of cost effective large scale energy storage since nobody knows how it might be done. With current and foreseeable technology wind and PV are, and will remain, an expensive distraction.

Dear Stuart,
I agree it’s a vital area for some focus. Apart from the capital cost ,what is often glossed over ( as in the case of air liquefacation) is the energy cost or loss in the conversion from input to output of the various storage batteries. Thermal storage will be as important as electrical storage as we try to extract more useful work from our waste streams.